Merge branch '771-create-bramble-modules'

.gitignore

@@ -21,3 +21,5 @@ local.properties
 .gradle
 build/
 *.iml
+.gitignore
+src/test/

bramble-android/.gitignore

@@ -0,0 +1,5 @@
+bin
+gen
+build
+.settings
+src/main/res/raw/*.zip

bramble-android/build.gradle

@@ -0,0 +1,104 @@
+import de.undercouch.gradle.tasks.download.Download
+import de.undercouch.gradle.tasks.download.Verify
+
+apply plugin: 'com.android.library'
+apply plugin: 'witness'
+apply plugin: 'de.undercouch.download'
+
+android {
+	compileSdkVersion 23
+	buildToolsVersion "23.0.3"
+
+	defaultConfig {
+		minSdkVersion 14
+		targetSdkVersion 22
+		versionCode 1
+		versionName "1.0"
+		consumerProguardFiles 'proguard-rules.txt'
+	}
+
+	compileOptions {
+		sourceCompatibility JavaVersion.VERSION_1_7
+		targetCompatibility JavaVersion.VERSION_1_7
+	}
+}
+
+dependencies {
+	compile project(':bramble-core')
+	compile fileTree(dir: 'libs', include: ['*.jar'])
+	provided 'javax.annotation:jsr250-api:1.0'
+}
+
+def torBinaryDir = 'src/main/res/raw'
+
+task downloadTorGeoIp(type: Download) {
+	src 'https://briarproject.org/build/geoip-2015-12-01.zip'
+	dest "$torBinaryDir/geoip.zip"
+	onlyIfNewer true
+}
+
+task downloadTorBinaryArm(type: Download) {
+	src 'https://briarproject.org/build/tor-0.2.7.6-arm.zip'
+	dest "$torBinaryDir/tor_arm.zip"
+	onlyIfNewer true
+}
+
+task downloadTorBinaryArmPie(type: Download) {
+	src 'https://briarproject.org/build/tor-0.2.7.6-arm-pie.zip'
+	dest "$torBinaryDir/tor_arm_pie.zip"
+	onlyIfNewer true
+}
+
+task downloadTorBinaryX86(type: Download) {
+	src 'https://briarproject.org/build/tor-0.2.7.6-x86.zip'
+	dest "$torBinaryDir/tor_x86.zip"
+	onlyIfNewer true
+}
+
+task downloadTorBinaryX86Pie(type: Download) {
+	src 'https://briarproject.org/build/tor-0.2.7.6-x86-pie.zip'
+	dest "$torBinaryDir/tor_x86_pie.zip"
+	onlyIfNewer true
+}
+
+task verifyTorGeoIp(type: Verify, dependsOn: 'downloadTorGeoIp') {
+	src "$torBinaryDir/geoip.zip"
+	algorithm 'SHA-256'
+	checksum '9bcdaf0a7ba0933735328d8ec466c25c25dbb459efc2bce9e55c774eabea5162'
+}
+
+task verifyTorBinaryArm(type: Verify, dependsOn: 'downloadTorBinaryArm') {
+	src "$torBinaryDir/tor_arm.zip"
+	algorithm 'SHA-256'
+	checksum '83272962eda701cd5d74d2418651c4ff0f0b1dff51f558a292d1a1c42bf12146'
+}
+
+task verifyTorBinaryArmPie(type: Verify, dependsOn: 'downloadTorBinaryArmPie') {
+	src "$torBinaryDir/tor_arm_pie.zip"
+	algorithm 'SHA-256'
+	checksum 'd0300d1e45de11ebb24ed62b9c492be9c2e88590b7822195ab38c7a76ffcf646'
+}
+
+task verifyTorBinaryX86(type: Verify, dependsOn: 'downloadTorBinaryX86') {
+	src "$torBinaryDir/tor_x86.zip"
+	algorithm 'SHA-256'
+	checksum 'b8813d97b01ee1b9c9a4233c1b9bbe9f9f6b494ae6f9cbd84de8a3911911615e'
+}
+
+task verifyTorBinaryX86Pie(type: Verify, dependsOn: 'downloadTorBinaryX86Pie') {
+	src "$torBinaryDir/tor_x86_pie.zip"
+	algorithm 'SHA-256'
+	checksum '9c66e765aa196dc089951a1b2140cc8290305c2fcbf365121f99e01a233baf4e'
+}
+
+project.afterEvaluate {
+	preBuild.dependsOn {
+		[
+				'verifyTorGeoIp',
+				'verifyTorBinaryArm',
+				'verifyTorBinaryArmPie',
+				'verifyTorBinaryX86',
+				'verifyTorBinaryX86Pie'
+		]
+	}
+}

bramble-android/proguard-rules.txt

@@ -0,0 +1,15 @@
+-keep,includedescriptorclasses class org.briarproject.** { *; }
+
+-keep class org.h2.** { *; }
+-dontwarn org.h2.**
+-dontnote org.h2.**
+
+-keep class dagger.** { *; }
+-dontwarn dagger.**
+-dontnote dagger.**
+
+-dontwarn sun.misc.Unsafe
+-dontnote com.google.common.**
+
+# UPnP library isn't used
+-dontwarn org.bitlet.weupnp.**

bramble-android/src/main/AndroidManifest.xml

@@ -0,0 +1,24 @@
+<manifest
+	package="org.briarproject.bramble"
+	xmlns:android="http://schemas.android.com/apk/res/android">
+
+	<uses-feature android:name="android.hardware.bluetooth"/>
+
+	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
+	<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
+	<uses-permission android:name="android.permission.BLUETOOTH"/>
+	<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
+	<uses-permission android:name="android.permission.INTERNET"/>
+	<uses-permission android:name="android.permission.READ_LOGS"/>
+	<uses-permission android:name="android.permission.WAKE_LOCK"/>
+	<!-- Since API 23, this is needed to add contacts via Bluetooth -->
+	<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
+
+	<application
+		android:allowBackup="false"
+		android:label="@string/app_name"
+		android:supportsRtl="true">
+
+	</application>
+
+</manifest>

bramble-android/src/main/java/org/briarproject/bramble/BrambleAndroidModule.java

@@ -0,0 +1,13 @@
+package org.briarproject.bramble;
+
+import org.briarproject.bramble.plugin.AndroidPluginModule;
+import org.briarproject.bramble.system.AndroidSystemModule;
+
+import dagger.Module;
+
+@Module(includes = {
+		AndroidPluginModule.class,
+		AndroidSystemModule.class
+})
+public class BrambleAndroidModule {
+}

bramble-android/src/main/java/org/briarproject/bramble/api/system/AndroidExecutor.java

@@ -1,4 +1,4 @@
-package org.briarproject.android.api;
+package org.briarproject.bramble.api.system;
 
 import java.util.concurrent.Callable;
 import java.util.concurrent.Future;

bramble-android/src/main/java/org/briarproject/bramble/plugin/AndroidPluginModule.java

@@ -1,20 +1,21 @@
-package org.briarproject.plugins;
+package org.briarproject.bramble.plugin;
 
 import android.app.Application;
 import android.content.Context;
 
-import org.briarproject.android.api.AndroidExecutor;
-import org.briarproject.api.event.EventBus;
-import org.briarproject.api.lifecycle.IoExecutor;
-import org.briarproject.api.plugins.BackoffFactory;
-import org.briarproject.api.plugins.PluginConfig;
-import org.briarproject.api.plugins.duplex.DuplexPluginFactory;
-import org.briarproject.api.plugins.simplex.SimplexPluginFactory;
-import org.briarproject.api.reporting.DevReporter;
-import org.briarproject.api.system.LocationUtils;
-import org.briarproject.plugins.droidtooth.DroidtoothPluginFactory;
-import org.briarproject.plugins.tcp.AndroidLanTcpPluginFactory;
-import org.briarproject.plugins.tor.TorPluginFactory;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.PluginConfig;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
+import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
+import org.briarproject.bramble.api.reporting.DevReporter;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.api.system.LocationUtils;
+import org.briarproject.bramble.plugin.droidtooth.DroidtoothPluginFactory;
+import org.briarproject.bramble.plugin.tcp.AndroidLanTcpPluginFactory;
+import org.briarproject.bramble.plugin.tor.TorPluginFactory;
 
 import java.security.SecureRandom;
 import java.util.Arrays;
@@ -28,10 +29,10 @@ import dagger.Module;
 import dagger.Provides;
 
 @Module
-public class AndroidPluginsModule {
+public class AndroidPluginModule {
 
 	@Provides
-	public PluginConfig providePluginConfig(@IoExecutor Executor ioExecutor,
+	PluginConfig providePluginConfig(@IoExecutor Executor ioExecutor,
 			AndroidExecutor androidExecutor, SecureRandom random,
 			SocketFactory torSocketFactory, BackoffFactory backoffFactory,
 			Application app, LocationUtils locationUtils, DevReporter reporter,
@@ -46,7 +47,8 @@ public class AndroidPluginsModule {
 				backoffFactory, appContext);
 		final Collection<DuplexPluginFactory> duplex =
 				Arrays.asList(bluetooth, tor, lan);
-		return new PluginConfig() {
+		@NotNullByDefault
+		PluginConfig pluginConfig = new PluginConfig() {
 
 			@Override
 			public Collection<DuplexPluginFactory> getDuplexFactories() {
@@ -58,5 +60,6 @@ public class AndroidPluginsModule {
 				return Collections.emptyList();
 			}
 		};
+		return pluginConfig;
 	}
 }

bramble-android/src/main/java/org/briarproject/bramble/plugin/droidtooth/DroidtoothPlugin.java

@@ -1,4 +1,4 @@
-package org.briarproject.plugins.droidtooth;
+package org.briarproject.bramble.plugin.droidtooth;
 
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothDevice;
@@ -9,23 +9,23 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 
-import org.briarproject.android.api.AndroidExecutor;
-import org.briarproject.android.util.AndroidUtils;
-import org.briarproject.api.FormatException;
-import org.briarproject.api.TransportId;
-import org.briarproject.api.contact.ContactId;
-import org.briarproject.api.crypto.PseudoRandom;
-import org.briarproject.api.data.BdfList;
-import org.briarproject.api.keyagreement.KeyAgreementConnection;
-import org.briarproject.api.keyagreement.KeyAgreementListener;
-import org.briarproject.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.api.plugins.Backoff;
-import org.briarproject.api.plugins.duplex.DuplexPlugin;
-import org.briarproject.api.plugins.duplex.DuplexPluginCallback;
-import org.briarproject.api.plugins.duplex.DuplexTransportConnection;
-import org.briarproject.api.properties.TransportProperties;
-import org.briarproject.util.StringUtils;
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.crypto.PseudoRandom;
+import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.util.AndroidUtils;
+import org.briarproject.bramble.util.StringUtils;
 
 import java.io.Closeable;
 import java.io.IOException;
@@ -64,12 +64,12 @@ import static android.bluetooth.BluetoothDevice.EXTRA_DEVICE;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_BLUETOOTH;
-import static org.briarproject.api.plugins.BluetoothConstants.ID;
-import static org.briarproject.api.plugins.BluetoothConstants.PROP_ADDRESS;
-import static org.briarproject.api.plugins.BluetoothConstants.PROP_UUID;
-import static org.briarproject.api.plugins.BluetoothConstants.UUID_BYTES;
-import static org.briarproject.util.PrivacyUtils.scrubMacAddress;
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_BLUETOOTH;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_UUID;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.UUID_BYTES;
+import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault

bramble-android/src/main/java/org/briarproject/bramble/plugin/droidtooth/DroidtoothPluginFactory.java

@@ -1,20 +1,25 @@
-package org.briarproject.plugins.droidtooth;
+package org.briarproject.bramble.plugin.droidtooth;
 
 import android.content.Context;
 
-import org.briarproject.android.api.AndroidExecutor;
-import org.briarproject.api.TransportId;
-import org.briarproject.api.plugins.Backoff;
-import org.briarproject.api.plugins.BackoffFactory;
-import org.briarproject.api.plugins.duplex.DuplexPlugin;
-import org.briarproject.api.plugins.duplex.DuplexPluginCallback;
-import org.briarproject.api.plugins.duplex.DuplexPluginFactory;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
+import org.briarproject.bramble.api.system.AndroidExecutor;
 
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
 
-import static org.briarproject.api.plugins.BluetoothConstants.ID;
+import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
+
+@Immutable
+@NotNullByDefault
 public class DroidtoothPluginFactory implements DuplexPluginFactory {
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds

bramble-android/src/main/java/org/briarproject/bramble/plugin/droidtooth/DroidtoothTransportConnection.java

@@ -1,14 +1,16 @@
-package org.briarproject.plugins.droidtooth;
+package org.briarproject.bramble.plugin.droidtooth;
 
 import android.bluetooth.BluetoothSocket;
 
-import org.briarproject.api.plugins.Plugin;
-import org.briarproject.api.plugins.duplex.AbstractDuplexTransportConnection;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Plugin;
+import org.briarproject.bramble.api.plugin.duplex.AbstractDuplexTransportConnection;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 
+@NotNullByDefault
 class DroidtoothTransportConnection extends AbstractDuplexTransportConnection {
 
 	private final BluetoothSocket socket;

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java

@@ -1,4 +1,4 @@
-package org.briarproject.plugins.tcp;
+package org.briarproject.bramble.plugin.tcp;
 
 import android.content.BroadcastReceiver;
 import android.content.Context;
@@ -7,9 +7,9 @@ import android.content.IntentFilter;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 
-import org.briarproject.api.nullsafety.NotNullByDefault;
-import org.briarproject.api.plugins.Backoff;
-import org.briarproject.api.plugins.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPluginFactory.java

@@ -1,18 +1,23 @@
-package org.briarproject.plugins.tcp;
+package org.briarproject.bramble.plugin.tcp;
 
 import android.content.Context;
 
-import org.briarproject.api.TransportId;
-import org.briarproject.api.plugins.Backoff;
-import org.briarproject.api.plugins.BackoffFactory;
-import org.briarproject.api.plugins.duplex.DuplexPlugin;
-import org.briarproject.api.plugins.duplex.DuplexPluginCallback;
-import org.briarproject.api.plugins.duplex.DuplexPluginFactory;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 
 import java.util.concurrent.Executor;
 
-import static org.briarproject.api.plugins.LanTcpConstants.ID;
+import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
+
+@Immutable
+@NotNullByDefault
 public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorNetworkMetadata.java

@@ -1,18 +1,18 @@
-package org.briarproject.plugins.tor;
+package org.briarproject.bramble.plugin.tor;
 
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Set;
 
-public class TorNetworkMetadata {
+class TorNetworkMetadata {
 
 	// See https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
 	// and https://trac.torproject.org/projects/tor/wiki/doc/OONI/censorshipwiki
 	// TODO: get a more complete list
 	private static final Set<String> BLOCKED_IN_COUNTRIES =
-			new HashSet<String>(Arrays.asList("CN", "IR", "SY", "ZZ"));
+			new HashSet<>(Arrays.asList("CN", "IR", "SY", "ZZ"));
 
-	public static boolean isTorProbablyBlocked(String countryCode) {
+	static boolean isTorProbablyBlocked(String countryCode) {
 		return BLOCKED_IN_COUNTRIES.contains(countryCode);
 	}
 }

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorPlugin.java

@@ -1,4 +1,4 @@
-package org.briarproject.plugins.tor;
+package org.briarproject.bramble.plugin.tor;
 
 import android.content.BroadcastReceiver;
 import android.content.Context;
@@ -7,6 +7,7 @@ import android.content.IntentFilter;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
+import android.content.res.Resources;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 import android.os.FileObserver;
@@ -15,27 +16,28 @@ import android.os.PowerManager;
 import net.freehaven.tor.control.EventHandler;
 import net.freehaven.tor.control.TorControlConnection;
 
-import org.briarproject.android.util.AndroidUtils;
-import org.briarproject.api.TransportId;
-import org.briarproject.api.contact.ContactId;
-import org.briarproject.api.crypto.PseudoRandom;
-import org.briarproject.api.data.BdfList;
-import org.briarproject.api.event.Event;
-import org.briarproject.api.event.EventListener;
-import org.briarproject.api.event.SettingsUpdatedEvent;
-import org.briarproject.api.keyagreement.KeyAgreementListener;
-import org.briarproject.api.nullsafety.NotNullByDefault;
-import org.briarproject.api.plugins.Backoff;
-import org.briarproject.api.plugins.TorConstants;
-import org.briarproject.api.plugins.duplex.DuplexPlugin;
-import org.briarproject.api.plugins.duplex.DuplexPluginCallback;
-import org.briarproject.api.plugins.duplex.DuplexTransportConnection;
-import org.briarproject.api.properties.TransportProperties;
-import org.briarproject.api.reporting.DevReporter;
-import org.briarproject.api.settings.Settings;
-import org.briarproject.api.system.LocationUtils;
-import org.briarproject.util.IoUtils;
-import org.briarproject.util.StringUtils;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.crypto.PseudoRandom;
+import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.TorConstants;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.api.reporting.DevReporter;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
+import org.briarproject.bramble.api.system.LocationUtils;
+import org.briarproject.bramble.util.AndroidUtils;
+import org.briarproject.bramble.util.IoUtils;
+import org.briarproject.bramble.util.StringUtils;
 
 import java.io.Closeable;
 import java.io.EOFException;
@@ -75,10 +77,11 @@ import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static net.freehaven.tor.control.TorControlCommands.HS_ADDRESS;
 import static net.freehaven.tor.control.TorControlCommands.HS_PRIVKEY;
-import static org.briarproject.api.plugins.TorConstants.CONTROL_PORT;
-import static org.briarproject.util.PrivacyUtils.scrubOnion;
+import static org.briarproject.bramble.api.plugin.TorConstants.CONTROL_PORT;
+import static org.briarproject.bramble.util.PrivacyUtils.scrubOnion;
 
-@NotNullByDefault
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	private static final String PROP_ONION = "onion";
@@ -107,13 +110,9 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
 	private volatile boolean running = false;
-	@Nullable
 	private volatile ServerSocket socket = null;
-	@Nullable
 	private volatile Socket controlSocket = null;
-	@Nullable
 	private volatile TorControlConnection controlConnection = null;
-	@Nullable
 	private volatile BroadcastReceiver networkStateReceiver = null;
 
 	TorPlugin(Executor ioExecutor, Context appContext,
@@ -277,23 +276,29 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private InputStream getTorInputStream() throws IOException {
 		if (LOG.isLoggable(INFO))
 			LOG.info("Installing Tor binary for " + architecture);
-		String filename = "tor-" + architecture + ".zip";
-		InputStream in = appContext.getResources().getAssets().open(filename);
+		int resId = getResourceId("tor_" + architecture);
+		InputStream in = appContext.getResources().openRawResource(resId);
 		ZipInputStream zin = new ZipInputStream(in);
 		if (zin.getNextEntry() == null) throw new IOException();
 		return zin;
 	}
 
 	private InputStream getGeoIpInputStream() throws IOException {
-		String filename = "geoip.zip";
-		InputStream in = appContext.getResources().getAssets().open(filename);
+		int resId = getResourceId("geoip");
+		InputStream in = appContext.getResources().openRawResource(resId);
 		ZipInputStream zin = new ZipInputStream(in);
 		if (zin.getNextEntry() == null) throw new IOException();
 		return zin;
 	}
 
 	private InputStream getConfigInputStream() throws IOException {
-		return appContext.getResources().getAssets().open("torrc");
+		int resId = getResourceId("torrc");
+		return appContext.getResources().openRawResource(resId);
+	}
+
+	private int getResourceId(String filename) {
+		Resources res = appContext.getResources();
+		return res.getIdentifier(filename, "raw", appContext.getPackageName());
 	}
 
 	private void tryToClose(@Nullable Closeable c) {

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorPluginFactory.java

@@ -1,25 +1,29 @@
-package org.briarproject.plugins.tor;
+package org.briarproject.bramble.plugin.tor;
 
 import android.content.Context;
 import android.os.Build;
 
-import org.briarproject.android.util.AndroidUtils;
-import org.briarproject.api.TransportId;
-import org.briarproject.api.event.EventBus;
-import org.briarproject.api.plugins.Backoff;
-import org.briarproject.api.plugins.BackoffFactory;
-import org.briarproject.api.plugins.TorConstants;
-import org.briarproject.api.plugins.duplex.DuplexPlugin;
-import org.briarproject.api.plugins.duplex.DuplexPluginCallback;
-import org.briarproject.api.plugins.duplex.DuplexPluginFactory;
-import org.briarproject.api.reporting.DevReporter;
-import org.briarproject.api.system.LocationUtils;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.TorConstants;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
+import org.briarproject.bramble.api.reporting.DevReporter;
+import org.briarproject.bramble.api.system.LocationUtils;
+import org.briarproject.bramble.util.AndroidUtils;
 
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
+import javax.annotation.concurrent.Immutable;
 import javax.net.SocketFactory;
 
+@Immutable
+@NotNullByDefault
 public class TorPluginFactory implements DuplexPluginFactory {
 
 	private static final Logger LOG =
@@ -81,7 +85,7 @@ public class TorPluginFactory implements DuplexPluginFactory {
 			return null;
 		}
 		// Use position-independent executable for SDK >= 16
-		if (Build.VERSION.SDK_INT >= 16) architecture += "-pie";
+		if (Build.VERSION.SDK_INT >= 16) architecture += "_pie";
 
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorTransportConnection.java

@@ -1,13 +1,15 @@
-package org.briarproject.plugins.tor;
+package org.briarproject.bramble.plugin.tor;
 
-import org.briarproject.api.plugins.Plugin;
-import org.briarproject.api.plugins.duplex.AbstractDuplexTransportConnection;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Plugin;
+import org.briarproject.bramble.api.plugin.duplex.AbstractDuplexTransportConnection;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.net.Socket;
 
+@NotNullByDefault
 class TorTransportConnection extends AbstractDuplexTransportConnection {
 
 	private final Socket socket;

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidExecutorImpl.java

@@ -1,10 +1,10 @@
-package org.briarproject.system;
+package org.briarproject.bramble.system;
 
 import android.app.Application;
 import android.os.Handler;
 import android.os.Looper;
 
-import org.briarproject.android.api.AndroidExecutor;
+import org.briarproject.bramble.api.system.AndroidExecutor;
 
 import java.util.concurrent.Callable;
 import java.util.concurrent.CountDownLatch;

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidLocationUtils.java

@@ -1,4 +1,4 @@
-package org.briarproject.system;
+package org.briarproject.bramble.system;
 
 import android.annotation.SuppressLint;
 import android.app.Application;
@@ -6,7 +6,8 @@ import android.content.Context;
 import android.telephony.TelephonyManager;
 import android.text.TextUtils;
 
-import org.briarproject.api.system.LocationUtils;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.LocationUtils;
 
 import java.util.Locale;
 import java.util.logging.Logger;
@@ -15,6 +16,7 @@ import javax.inject.Inject;
 
 import static android.content.Context.TELEPHONY_SERVICE;
 
+@NotNullByDefault
 class AndroidLocationUtils implements LocationUtils {
 
 	private static final Logger LOG =
@@ -23,7 +25,7 @@ class AndroidLocationUtils implements LocationUtils {
 	private final Context appContext;
 
 	@Inject
-	public AndroidLocationUtils(Application app) {
+	AndroidLocationUtils(Application app) {
 		appContext = app.getApplicationContext();
 	}
 
@@ -44,6 +46,7 @@ class AndroidLocationUtils implements LocationUtils {
 	 * some reason - both that class and {@code Context.COUNTRY_CODE} are
 	 * annotated {@code @hide}.
 	 */
+	@Override
 	@SuppressLint("DefaultLocale")
 	public String getCurrentCountry() {
 		String countryCode = getCountryFromPhoneNetwork();

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidSeedProvider.java

@@ -1,4 +1,4 @@
-package org.briarproject.system;
+package org.briarproject.bramble.system;
 
 import android.app.Application;
 import android.content.ContentResolver;
@@ -6,13 +6,18 @@ import android.content.Context;
 import android.os.Build;
 import android.provider.Settings;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
 import java.io.DataOutputStream;
 import java.io.IOException;
 
+import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
 import static android.provider.Settings.Secure.ANDROID_ID;
 
+@Immutable
+@NotNullByDefault
 class AndroidSeedProvider extends LinuxSeedProvider {
 
 	private final Context appContext;

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidSystemModule.java

@@ -0,0 +1,33 @@
+package org.briarproject.bramble.system;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.api.system.LocationUtils;
+import org.briarproject.bramble.api.system.SeedProvider;
+
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class AndroidSystemModule {
+
+	@Provides
+	@Singleton
+	SeedProvider provideSeedProvider(Application app) {
+		return new AndroidSeedProvider(app);
+	}
+
+	@Provides
+	LocationUtils provideLocationUtils(Application app) {
+		return new AndroidLocationUtils(app);
+	}
+
+	@Provides
+	@Singleton
+	AndroidExecutor provideAndroidExecutor(Application app) {
+		return new AndroidExecutorImpl(app);
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java

@@ -0,0 +1,70 @@
+package org.briarproject.bramble.util;
+
+import android.bluetooth.BluetoothAdapter;
+import android.content.Context;
+import android.os.Build;
+import android.provider.Settings;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+
+import static android.content.Context.MODE_PRIVATE;
+
+public class AndroidUtils {
+
+	// Fake Bluetooth address returned by BluetoothAdapter on API 23 and later
+	private static final String FAKE_BLUETOOTH_ADDRESS = "02:00:00:00:00:00";
+
+	private static final String STORED_REPORTS = "dev-reports";
+
+	@SuppressWarnings("deprecation")
+	public static Collection<String> getSupportedArchitectures() {
+		List<String> abis = new ArrayList<>();
+		if (Build.VERSION.SDK_INT >= 21) {
+			abis.addAll(Arrays.asList(Build.SUPPORTED_ABIS));
+		} else {
+			abis.add(Build.CPU_ABI);
+			if (Build.CPU_ABI2 != null) abis.add(Build.CPU_ABI2);
+		}
+		return abis;
+	}
+
+	public static String getBluetoothAddress(Context ctx,
+			BluetoothAdapter adapter) {
+		// Return the adapter's address if it's valid and not fake
+		String address = adapter.getAddress();
+		if (isValidBluetoothAddress(address)) return address;
+		// Return the address from settings if it's valid and not fake
+		address = Settings.Secure.getString(ctx.getContentResolver(),
+				"bluetooth_address");
+		if (isValidBluetoothAddress(address)) return address;
+		// Let the caller know we can't find the address
+		return "";
+	}
+
+	private static boolean isValidBluetoothAddress(String address) {
+		return !StringUtils.isNullOrEmpty(address)
+				&& BluetoothAdapter.checkBluetoothAddress(address)
+				&& !address.equals(FAKE_BLUETOOTH_ADDRESS);
+	}
+
+	public static void deleteAppData(Context ctx) {
+		File dataDir = new File(ctx.getApplicationInfo().dataDir);
+		File[] children = dataDir.listFiles();
+		if (children != null) {
+			for (File child : children) {
+				if (!child.getName().equals("lib"))
+					IoUtils.deleteFileOrDir(child);
+			}
+		}
+		// Recreate the cache dir as some OpenGL drivers expect it to exist
+		new File(dataDir, "cache").mkdir();
+	}
+
+	public static File getReportDir(Context ctx) {
+		return ctx.getDir(STORED_REPORTS, MODE_PRIVATE);
+	}
+}

bramble-android/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+	<string name="app_name">Bramble</string>
+</resources>

bramble-api/build.gradle

@@ -0,0 +1,22 @@
+apply plugin: 'java'
+sourceCompatibility = 1.6
+targetCompatibility = 1.6
+
+apply plugin: 'witness'
+
+dependencies {
+	compile "com.google.dagger:dagger:2.0.2"
+	compile 'com.google.dagger:dagger-compiler:2.0.2'
+	compile 'com.google.code.findbugs:jsr305:3.0.1'
+}
+
+dependencyVerification {
+	verify = [
+			'com.google.dagger:dagger:84c0282ed8be73a29e0475d639da030b55dee72369e58dd35ae7d4fe6243dcf9',
+			'com.google.dagger:dagger-compiler:b74bc9de063dd4c6400b232231f2ef5056145b8fbecbf5382012007dd1c071b3',
+			'javax.inject:javax.inject:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
+			'com.google.dagger:dagger-producers:99ec15e8a0507ba569e7655bc1165ee5e5ca5aa914b3c8f7e2c2458f724edd6b',
+			'com.google.guava:guava:d664fbfc03d2e5ce9cab2a44fb01f1d0bf9dfebeccc1a473b1f9ea31f79f6f99',
+			'com.google.code.findbugs:jsr305:c885ce34249682bc0236b4a7d56efcc12048e6135a5baf7a9cde8ad8cda13fcd'
+	]
+}

bramble-api/src/main/java/org/briarproject/bramble/api/Bytes.java

@@ -1,11 +1,17 @@
-package org.briarproject.api;
+package org.briarproject.bramble.api;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.util.Arrays;
 import java.util.Comparator;
 
+import javax.annotation.concurrent.ThreadSafe;
+
 /**
  * A wrapper around a byte array, to allow it to be stored in maps etc.
  */
+@ThreadSafe
+@NotNullByDefault
 public class Bytes implements Comparable<Bytes> {
 
 	public static final BytesComparator COMPARATOR = new BytesComparator();

bramble-api/src/main/java/org/briarproject/bramble/api/FormatException.java

@@ -0,0 +1,9 @@
+package org.briarproject.bramble.api;
+
+import java.io.IOException;
+
+/**
+ * An exception that indicates an unrecoverable formatting error.
+ */
+public class FormatException extends IOException {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/StringMap.java

@@ -1,12 +1,10 @@
-package org.briarproject.api;
+package org.briarproject.bramble.api;
 
 import java.util.Hashtable;
 import java.util.Map;
 
 public abstract class StringMap extends Hashtable<String, String> {
 
-	private static final long serialVersionUID = 2497176435908100448L;
-
 	protected StringMap(Map<String, String> m) {
 		super(m);
 	}

bramble-api/src/main/java/org/briarproject/bramble/api/UniqueId.java

@@ -0,0 +1,20 @@
+package org.briarproject.bramble.api;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.ThreadSafe;
+
+@ThreadSafe
+@NotNullByDefault
+public abstract class UniqueId extends Bytes {
+
+	/**
+	 * The length of a unique identifier in bytes.
+	 */
+	public static final int LENGTH = 32;
+
+	protected UniqueId(byte[] id) {
+		super(id);
+		if (id.length != LENGTH) throw new IllegalArgumentException();
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/client/BdfMessageContext.java

@@ -1,8 +1,8 @@
-package org.briarproject.api.clients;
+package org.briarproject.bramble.api.client;
 
-import org.briarproject.api.data.BdfDictionary;
-import org.briarproject.api.nullsafety.NotNullByDefault;
-import org.briarproject.api.sync.MessageId;
+import org.briarproject.bramble.api.data.BdfDictionary;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
 
 import java.util.Collection;
 import java.util.Collections;

bramble-api/src/main/java/org/briarproject/bramble/api/client/BdfMessageValidator.java

@@ -0,0 +1,66 @@
+package org.briarproject.bramble.api.client;
+
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.data.MetadataEncoder;
+import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.Group;
+import org.briarproject.bramble.api.sync.InvalidMessageException;
+import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.sync.MessageContext;
+import org.briarproject.bramble.api.sync.ValidationManager.MessageValidator;
+import org.briarproject.bramble.api.system.Clock;
+
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
+import static org.briarproject.bramble.api.transport.TransportConstants.MAX_CLOCK_DIFFERENCE;
+
+@Immutable
+@NotNullByDefault
+public abstract class BdfMessageValidator implements MessageValidator {
+
+	protected static final Logger LOG =
+			Logger.getLogger(BdfMessageValidator.class.getName());
+
+	protected final ClientHelper clientHelper;
+	protected final MetadataEncoder metadataEncoder;
+	protected final Clock clock;
+
+	protected BdfMessageValidator(ClientHelper clientHelper,
+			MetadataEncoder metadataEncoder, Clock clock) {
+		this.clientHelper = clientHelper;
+		this.metadataEncoder = metadataEncoder;
+		this.clock = clock;
+	}
+
+	protected abstract BdfMessageContext validateMessage(Message m, Group g,
+			BdfList body) throws InvalidMessageException, FormatException;
+
+	@Override
+	public MessageContext validateMessage(Message m, Group g)
+			throws InvalidMessageException {
+		// Reject the message if it's too far in the future
+		long now = clock.currentTimeMillis();
+		if (m.getTimestamp() - now > MAX_CLOCK_DIFFERENCE) {
+			throw new InvalidMessageException(
+					"Timestamp is too far in the future");
+		}
+		byte[] raw = m.getRaw();
+		if (raw.length <= MESSAGE_HEADER_LENGTH) {
+			throw new InvalidMessageException("Message is too short");
+		}
+		try {
+			BdfList body = clientHelper.toList(raw, MESSAGE_HEADER_LENGTH,
+					raw.length - MESSAGE_HEADER_LENGTH);
+			BdfMessageContext result = validateMessage(m, g, body);
+			Metadata meta = metadataEncoder.encode(result.getDictionary());
+			return new MessageContext(meta, result.getDependencies());
+		} catch (FormatException e) {
+			throw new InvalidMessageException(e);
+		}
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/client/ClientHelper.java

@@ -1,14 +1,14 @@
-package org.briarproject.api.clients;
+package org.briarproject.bramble.api.client;
 
-import org.briarproject.api.FormatException;
-import org.briarproject.api.data.BdfDictionary;
-import org.briarproject.api.data.BdfList;
-import org.briarproject.api.db.DbException;
-import org.briarproject.api.db.Transaction;
-import org.briarproject.api.nullsafety.NotNullByDefault;
-import org.briarproject.api.sync.GroupId;
-import org.briarproject.api.sync.Message;
-import org.briarproject.api.sync.MessageId;
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.data.BdfDictionary;
+import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.sync.MessageId;
 
 import java.security.GeneralSecurityException;
 import java.util.Map;
@@ -48,7 +48,8 @@ public interface ClientHelper {
 	BdfDictionary getGroupMetadataAsDictionary(Transaction txn, GroupId g)
 			throws DbException, FormatException;
 
-	BdfDictionary getMessageMetadataAsDictionary(MessageId m) throws DbException,
+	BdfDictionary getMessageMetadataAsDictionary(MessageId m)
+			throws DbException,
 			FormatException;
 
 	BdfDictionary getMessageMetadataAsDictionary(Transaction txn, MessageId m)

bramble-api/src/main/java/org/briarproject/bramble/api/client/ContactGroupFactory.java

@@ -0,0 +1,29 @@
+package org.briarproject.bramble.api.client;
+
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.ClientId;
+import org.briarproject.bramble.api.sync.Group;
+
+@NotNullByDefault
+public interface ContactGroupFactory {
+
+	/**
+	 * Creates a group that is not shared with any contacts.
+	 */
+	Group createLocalGroup(ClientId clientId);
+
+	/**
+	 * Creates a group for the given client to share with the given contact.
+	 */
+	Group createContactGroup(ClientId clientId, Contact contact);
+
+	/**
+	 * Creates a group for the given client to share between the given authors
+	 * identified by their AuthorIds.
+	 */
+	Group createContactGroup(ClientId clientId, AuthorId authorId1,
+			AuthorId authorId2);
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/Contact.java

@@ -1,8 +1,13 @@
-package org.briarproject.api.contact;
+package org.briarproject.bramble.api.contact;
 
-import org.briarproject.api.identity.Author;
-import org.briarproject.api.identity.AuthorId;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
 public class Contact {
 
 	private final ContactId id;

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactExchangeListener.java

@@ -0,0 +1,20 @@
+package org.briarproject.bramble.api.contact;
+
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface ContactExchangeListener {
+
+	void contactExchangeSucceeded(Author remoteAuthor);
+
+	/**
+	 * The exchange failed because the contact already exists.
+	 */
+	void duplicateContact(Author remoteAuthor);
+
+	/**
+	 * A general failure.
+	 */
+	void contactExchangeFailed();
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactExchangeTask.java

@@ -0,0 +1,22 @@
+package org.briarproject.bramble.api.contact;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+
+/**
+ * A task for conducting a contact information exchange with a remote peer.
+ */
+@NotNullByDefault
+public interface ContactExchangeTask {
+
+	/**
+	 * Exchanges contact information with a remote peer.
+	 */
+	void startExchange(ContactExchangeListener listener,
+			LocalAuthor localAuthor, SecretKey masterSecret,
+			DuplexTransportConnection conn, TransportId transportId,
+			boolean alice);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactId.java

@@ -1,9 +1,15 @@
-package org.briarproject.api.contact;
+package org.briarproject.bramble.api.contact;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
 
 /**
  * Type-safe wrapper for an integer that uniquely identifies a contact within
  * the scope of a single node.
  */
+@Immutable
+@NotNullByDefault
 public class ContactId {
 
 	private final int id;

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactManager.java

@@ -1,19 +1,25 @@
-package org.briarproject.api.contact;
+package org.briarproject.bramble.api.contact;
 
-import org.briarproject.api.crypto.SecretKey;
-import org.briarproject.api.db.DbException;
-import org.briarproject.api.db.Transaction;
-import org.briarproject.api.identity.Author;
-import org.briarproject.api.identity.AuthorId;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.util.Collection;
 
+@NotNullByDefault
 public interface ContactManager {
 
-	/** Registers a hook to be called whenever a contact is added. */
+	/**
+	 * Registers a hook to be called whenever a contact is added.
+	 */
 	void registerAddContactHook(AddContactHook hook);
 
-	/** Registers a hook to be called whenever a contact is removed. */
+	/**
+	 * Registers a hook to be called whenever a contact is removed.
+	 */
 	void registerRemoveContactHook(RemoveContactHook hook);
 
 	/**
@@ -32,27 +38,41 @@ public interface ContactManager {
 			SecretKey master, long timestamp, boolean alice, boolean verified,
 			boolean active) throws DbException;
 
-	/** Returns the contact with the given ID. */
+	/**
+	 * Returns the contact with the given ID.
+	 */
 	Contact getContact(ContactId c) throws DbException;
 
-	/** Returns all active contacts. */
+	/**
+	 * Returns all active contacts.
+	 */
 	Collection<Contact> getActiveContacts() throws DbException;
 
-	/** Removes a contact and all associated state. */
+	/**
+	 * Removes a contact and all associated state.
+	 */
 	void removeContact(ContactId c) throws DbException;
 
-	/** Removes a contact and all associated state. */
+	/**
+	 * Removes a contact and all associated state.
+	 */
 	void removeContact(Transaction txn, ContactId c) throws DbException;
 
-	/** Marks a contact as active or inactive. */
+	/**
+	 * Marks a contact as active or inactive.
+	 */
 	void setContactActive(Transaction txn, ContactId c, boolean active)
 			throws DbException;
 
-	/** Return true if a contact with this name and public key already exists */
+	/**
+	 * Return true if a contact with this name and public key already exists
+	 */
 	boolean contactExists(Transaction txn, AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException;
 
-	/** Return true if a contact with this name and public key already exists */
+	/**
+	 * Return true if a contact with this name and public key already exists
+	 */
 	boolean contactExists(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException;
 

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/ContactAddedEvent.java

@@ -0,0 +1,31 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a contact is added.
+ */
+@Immutable
+@NotNullByDefault
+public class ContactAddedEvent extends Event {
+
+	private final ContactId contactId;
+	private final boolean active;
+
+	public ContactAddedEvent(ContactId contactId, boolean active) {
+		this.contactId = contactId;
+		this.active = active;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	public boolean isActive() {
+		return active;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/ContactRemovedEvent.java

@@ -0,0 +1,25 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a contact is removed.
+ */
+@Immutable
+@NotNullByDefault
+public class ContactRemovedEvent extends Event {
+
+	private final ContactId contactId;
+
+	public ContactRemovedEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/ContactStatusChangedEvent.java

@@ -0,0 +1,31 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a contact is marked active or inactive.
+ */
+@Immutable
+@NotNullByDefault
+public class ContactStatusChangedEvent extends Event {
+
+	private final ContactId contactId;
+	private final boolean active;
+
+	public ContactStatusChangedEvent(ContactId contactId, boolean active) {
+		this.contactId = contactId;
+		this.active = active;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	public boolean isActive() {
+		return active;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/ContactVerifiedEvent.java

@@ -0,0 +1,26 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a contact is verified.
+ */
+@Immutable
+@NotNullByDefault
+public class ContactVerifiedEvent extends Event {
+
+	private final ContactId contactId;
+
+	public ContactVerifiedEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoComponent.java

@@ -1,7 +1,7 @@
-package org.briarproject.api.crypto;
+package org.briarproject.bramble.api.crypto;
 
-import org.briarproject.api.TransportId;
-import org.briarproject.api.transport.TransportKeys;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.security.GeneralSecurityException;
 import java.security.SecureRandom;

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoExecutor.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.crypto;
+package org.briarproject.bramble.api.crypto;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/KeyPair.java

@@ -1,6 +1,14 @@
-package org.briarproject.api.crypto;
+package org.briarproject.bramble.api.crypto;
 
-/** A key pair consisting of a {@link PublicKey} and a {@link PrivateKey). */
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A key pair consisting of a {@link PublicKey} and a {@link PrivateKey).
+ */
+@Immutable
+@NotNullByDefault
 public class KeyPair {
 
 	private final PublicKey publicKey;

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/KeyParser.java

@@ -1,7 +1,10 @@
-package org.briarproject.api.crypto;
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.security.GeneralSecurityException;
 
+@NotNullByDefault
 public interface KeyParser {
 
 	PublicKey parsePublicKey(byte[] encodedKey) throws GeneralSecurityException;

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/MessageDigest.java

@@ -0,0 +1,47 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface MessageDigest {
+
+	/**
+	 * @see {@link java.security.MessageDigest#digest()}
+	 */
+	byte[] digest();
+
+	/**
+	 * @see {@link java.security.MessageDigest#digest(byte[])}
+	 */
+	byte[] digest(byte[] input);
+
+	/**
+	 * @see {@link java.security.MessageDigest#digest(byte[], int, int)}
+	 */
+	int digest(byte[] buf, int offset, int len);
+
+	/**
+	 * @see {@link java.security.MessageDigest#getDigestLength()}
+	 */
+	int getDigestLength();
+
+	/**
+	 * @see {@link java.security.MessageDigest#reset()}
+	 */
+	void reset();
+
+	/**
+	 * @see {@link java.security.MessageDigest#update(byte)}
+	 */
+	void update(byte input);
+
+	/**
+	 * @see {@link java.security.MessageDigest#update(byte[])}
+	 */
+	void update(byte[] input);
+
+	/**
+	 * @see {@link java.security.MessageDigest#update(byte[], int, int)}
+	 */
+	void update(byte[] input, int offset, int len);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/PasswordStrengthEstimator.java

@@ -1,5 +1,8 @@
-package org.briarproject.api.crypto;
+package org.briarproject.bramble.api.crypto;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
 public interface PasswordStrengthEstimator {
 
 	float NONE = 0;

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/PrivateKey.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+/**
+ * The private half of a public/private {@link KeyPair}.
+ */
+@NotNullByDefault
+public interface PrivateKey {
+
+	/**
+	 * Returns the encoded representation of this key.
+	 */
+	byte[] getEncoded();
+}

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/PseudoRandom.java

@@ -0,0 +1,12 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+/**
+ * A deterministic pseudo-random number generator.
+ */
+@NotNullByDefault
+public interface PseudoRandom {
+
+	byte[] nextBytes(int bytes);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/PublicKey.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+/**
+ * The public half of a public/private {@link KeyPair}.
+ */
+@NotNullByDefault
+public interface PublicKey {
+
+	/**
+	 * Returns the encoded representation of this key.
+	 */
+	byte[] getEncoded();
+}

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/SecretKey.java

@@ -1,9 +1,14 @@
-package org.briarproject.api.crypto;
+package org.briarproject.bramble.api.crypto;
 
-/** A secret key used for encryption and/or authentication. */
+/**
+ * A secret key used for encryption and/or authentication.
+ */
 public class SecretKey {
 
-	public static final int LENGTH = 32; // Bytes
+	/**
+	 * The length of a secret key in bytes.
+	 */
+	public static final int LENGTH = 32;
 
 	private final byte[] key;
 

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/StreamDecrypter.java

@@ -1,13 +1,17 @@
-package org.briarproject.api.crypto;
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.IOException;
 
+@NotNullByDefault
 public interface StreamDecrypter {
 
 	/**
 	 * Reads a frame, decrypts its payload into the given buffer and returns
 	 * the payload length, or -1 if no more frames can be read from the stream.
-	 * @throws java.io.IOException if an error occurs while reading the frame,
+	 *
+	 * @throws IOException if an error occurs while reading the frame,
 	 * or if authenticated decryption fails.
 	 */
 	int readFrame(byte[] payload) throws IOException;

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/StreamDecrypterFactory.java

@@ -1,12 +1,16 @@
-package org.briarproject.api.crypto;
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.transport.StreamContext;
 
 import java.io.InputStream;
 
-import org.briarproject.api.transport.StreamContext;
-
+@NotNullByDefault
 public interface StreamDecrypterFactory {
 
-	/** Creates a {@link StreamDecrypter} for decrypting a transport stream. */
+	/**
+	 * Creates a {@link StreamDecrypter} for decrypting a transport stream.
+	 */
 	StreamDecrypter createStreamDecrypter(InputStream in, StreamContext ctx);
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/StreamEncrypter.java

@@ -0,0 +1,20 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.IOException;
+
+@NotNullByDefault
+public interface StreamEncrypter {
+
+	/**
+	 * Encrypts the given frame and writes it to the stream.
+	 */
+	void writeFrame(byte[] payload, int payloadLength, int paddingLength,
+			boolean finalFrame) throws IOException;
+
+	/**
+	 * Flushes the stream.
+	 */
+	void flush() throws IOException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/StreamEncrypterFactory.java

@@ -1,12 +1,16 @@
-package org.briarproject.api.crypto;
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.transport.StreamContext;
 
 import java.io.OutputStream;
 
-import org.briarproject.api.transport.StreamContext;
-
+@NotNullByDefault
 public interface StreamEncrypterFactory {
 
-	/** Creates a {@link StreamEncrypter} for encrypting a transport stream. */
+	/**
+	 * Creates a {@link StreamEncrypter} for encrypting a transport stream.
+	 */
 	StreamEncrypter createStreamEncrypter(OutputStream out, StreamContext ctx);
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfDictionary.java

@@ -1,7 +1,7 @@
-package org.briarproject.api.data;
+package org.briarproject.bramble.api.data;
 
-import org.briarproject.api.Bytes;
-import org.briarproject.api.FormatException;
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.FormatException;
 
 import java.util.Map;
 import java.util.concurrent.ConcurrentSkipListMap;

bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfEntry.java

@@ -1,7 +1,13 @@
-package org.briarproject.api.data;
+package org.briarproject.bramble.api.data;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.util.Map.Entry;
 
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
 public class BdfEntry implements Entry<String, Object>, Comparable<BdfEntry> {
 
 	private final String key;

bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfList.java

@@ -1,14 +1,15 @@
-package org.briarproject.api.data;
+package org.briarproject.bramble.api.data;
 
-import org.briarproject.api.Bytes;
-import org.briarproject.api.FormatException;
-import org.jetbrains.annotations.Nullable;
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.FormatException;
 
 import java.util.Arrays;
 import java.util.List;
 import java.util.Vector;
 
-import static org.briarproject.api.data.BdfDictionary.NULL_VALUE;
+import javax.annotation.Nullable;
+
+import static org.briarproject.bramble.api.data.BdfDictionary.NULL_VALUE;
 
 public class BdfList extends Vector<Object> {
 

bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfReader.java

@@ -1,49 +1,75 @@
-package org.briarproject.api.data;
+package org.briarproject.bramble.api.data;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.IOException;
 
+@NotNullByDefault
 public interface BdfReader {
 
 	int DEFAULT_NESTED_LIMIT = 5;
 
 	boolean eof() throws IOException;
+
 	void close() throws IOException;
 
 	boolean hasNull() throws IOException;
+
 	void readNull() throws IOException;
+
 	void skipNull() throws IOException;
 
 	boolean hasBoolean() throws IOException;
+
 	boolean readBoolean() throws IOException;
+
 	void skipBoolean() throws IOException;
 
 	boolean hasLong() throws IOException;
+
 	long readLong() throws IOException;
+
 	void skipLong() throws IOException;
 
 	boolean hasDouble() throws IOException;
+
 	double readDouble() throws IOException;
+
 	void skipDouble() throws IOException;
 
 	boolean hasString() throws IOException;
+
 	String readString(int maxLength) throws IOException;
+
 	void skipString() throws IOException;
 
 	boolean hasRaw() throws IOException;
+
 	byte[] readRaw(int maxLength) throws IOException;
+
 	void skipRaw() throws IOException;
 
 	boolean hasList() throws IOException;
+
 	BdfList readList() throws IOException;
+
 	void readListStart() throws IOException;
+
 	boolean hasListEnd() throws IOException;
+
 	void readListEnd() throws IOException;
+
 	void skipList() throws IOException;
 
 	boolean hasDictionary() throws IOException;
+
 	BdfDictionary readDictionary() throws IOException;
+
 	void readDictionaryStart() throws IOException;
+
 	boolean hasDictionaryEnd() throws IOException;
+
 	void readDictionaryEnd() throws IOException;
+
 	void skipDictionary() throws IOException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfReaderFactory.java

@@ -1,7 +1,10 @@
-package org.briarproject.api.data;
+package org.briarproject.bramble.api.data;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.InputStream;
 
+@NotNullByDefault
 public interface BdfReaderFactory {
 
 	BdfReader createReader(InputStream in);

bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfWriter.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.data;
+package org.briarproject.bramble.api.data;
 
 import java.io.IOException;
 import java.util.Collection;
@@ -7,20 +7,30 @@ import java.util.Map;
 public interface BdfWriter {
 
 	void flush() throws IOException;
+
 	void close() throws IOException;
 
 	void writeNull() throws IOException;
+
 	void writeBoolean(boolean b) throws IOException;
+
 	void writeLong(long l) throws IOException;
+
 	void writeDouble(double d) throws IOException;
+
 	void writeString(String s) throws IOException;
+
 	void writeRaw(byte[] b) throws IOException;
 
 	void writeList(Collection<?> c) throws IOException;
+
 	void writeListStart() throws IOException;
+
 	void writeListEnd() throws IOException;
 
 	void writeDictionary(Map<?, ?> m) throws IOException;
+
 	void writeDictionaryStart() throws IOException;
+
 	void writeDictionaryEnd() throws IOException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfWriterFactory.java

@@ -0,0 +1,11 @@
+package org.briarproject.bramble.api.data;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.OutputStream;
+
+@NotNullByDefault
+public interface BdfWriterFactory {
+
+	BdfWriter createWriter(OutputStream out);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/data/MetadataEncoder.java

@@ -0,0 +1,11 @@
+package org.briarproject.bramble.api.data;
+
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface MetadataEncoder {
+
+	Metadata encode(BdfDictionary d) throws FormatException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/data/MetadataParser.java

@@ -0,0 +1,11 @@
+package org.briarproject.bramble.api.data;
+
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface MetadataParser {
+
+	BdfDictionary parse(Metadata m) throws FormatException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/data/ObjectReader.java

@@ -0,0 +1,11 @@
+package org.briarproject.bramble.api.data;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.IOException;
+
+@NotNullByDefault
+public interface ObjectReader<T> {
+
+	T readObject(BdfReader r) throws IOException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/ContactExistsException.java

@@ -1,9 +1,8 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 /**
  * Thrown when a duplicate contact is added to the database. This exception may
  * occur due to concurrent updates and does not indicate a database error.
  */
 public class ContactExistsException extends DbException {
-
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -1,34 +1,38 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
-import org.briarproject.api.TransportId;
-import org.briarproject.api.contact.Contact;
-import org.briarproject.api.contact.ContactId;
-import org.briarproject.api.identity.Author;
-import org.briarproject.api.identity.AuthorId;
-import org.briarproject.api.identity.LocalAuthor;
-import org.briarproject.api.settings.Settings;
-import org.briarproject.api.sync.Ack;
-import org.briarproject.api.sync.ClientId;
-import org.briarproject.api.sync.Group;
-import org.briarproject.api.sync.Group.Visibility;
-import org.briarproject.api.sync.GroupId;
-import org.briarproject.api.sync.Message;
-import org.briarproject.api.sync.MessageId;
-import org.briarproject.api.sync.MessageStatus;
-import org.briarproject.api.sync.Offer;
-import org.briarproject.api.sync.Request;
-import org.briarproject.api.transport.TransportKeys;
-import org.jetbrains.annotations.Nullable;
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.sync.Ack;
+import org.briarproject.bramble.api.sync.ClientId;
+import org.briarproject.bramble.api.sync.Group;
+import org.briarproject.bramble.api.sync.Group.Visibility;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.sync.MessageStatus;
+import org.briarproject.bramble.api.sync.Offer;
+import org.briarproject.bramble.api.sync.Request;
+import org.briarproject.bramble.api.sync.ValidationManager;
+import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.Collection;
 import java.util.Map;
 
-import static org.briarproject.api.sync.ValidationManager.State;
+import javax.annotation.Nullable;
+
+import static org.briarproject.bramble.api.sync.ValidationManager.State;
 
 /**
  * Encapsulates the database implementation and exposes high-level operations
  * to other components.
  */
+@NotNullByDefault
 public interface DatabaseComponent {
 
 	/**
@@ -330,10 +334,10 @@ public interface DatabaseComponent {
 
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
-	 * Missing dependencies have the state {@link
-	 * org.briarproject.api.sync.ValidationManager.State UNKNOWN}.
-	 * Dependencies in other groups have the state {@link
-	 * org.briarproject.api.sync.ValidationManager.State INVALID}.
+	 * Missing dependencies have the state
+	 * {@link ValidationManager.State UNKNOWN}.
+	 * Dependencies in other groups have the state
+	 * {@link ValidationManager.State INVALID}.
 	 * Note that these states are not set on the dependencies themselves; the
 	 * returned states should only be taken in the context of the given message.
 	 * <p/>

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseConfig.java

@@ -1,9 +1,13 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
-import org.briarproject.api.crypto.SecretKey;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.File;
 
+import javax.annotation.Nullable;
+
+@NotNullByDefault
 public interface DatabaseConfig {
 
 	boolean databaseExists();
@@ -12,10 +16,12 @@ public interface DatabaseConfig {
 
 	void setEncryptionKey(SecretKey key);
 
+	@Nullable
 	SecretKey getEncryptionKey();
 
 	void setLocalAuthorName(String nickname);
 
+	@Nullable
 	String getLocalAuthorName();
 
 	long getMaxSize();

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseExecutor.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;
@@ -20,6 +20,7 @@ import static java.lang.annotation.RetentionPolicy.RUNTIME;
  * discarded.
  */
 @Qualifier
-@Target({ FIELD, METHOD, PARAMETER })
+@Target({FIELD, METHOD, PARAMETER})
 @Retention(RUNTIME)
-public @interface DatabaseExecutor {}
+public @interface DatabaseExecutor {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/DbClosedException.java

@@ -1,8 +1,7 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 /**
  * Thrown when a database operation is attempted and the database is closed.
  */
 public class DbClosedException extends DbException {
-
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/DbException.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 public class DbException extends Exception {
 

bramble-api/src/main/java/org/briarproject/bramble/api/db/Metadata.java

@@ -1,7 +1,10 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 import java.util.Hashtable;
 
+import javax.annotation.concurrent.ThreadSafe;
+
+@ThreadSafe
 public class Metadata extends Hashtable<String, byte[]> {
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/db/NoSuchContactException.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 /**
  * Thrown when a database operation is attempted for a contact that is not in
@@ -6,5 +6,4 @@ package org.briarproject.api.db;
  * not indicate a database error.
  */
 public class NoSuchContactException extends DbException {
-
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/NoSuchGroupException.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 /**
  * Thrown when a database operation is attempted for a group that is not in the
@@ -6,5 +6,4 @@ package org.briarproject.api.db;
  * indicate a database error.
  */
 public class NoSuchGroupException extends DbException {
-
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/NoSuchLocalAuthorException.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 /**
  * Thrown when a database operation is attempted for a pseudonym that is not in
@@ -6,5 +6,4 @@ package org.briarproject.api.db;
  * not indicate a database error.
  */
 public class NoSuchLocalAuthorException extends DbException {
-
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/NoSuchMessageException.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 /**
  * Thrown when a database operation is attempted for a message that is not in
@@ -6,5 +6,4 @@ package org.briarproject.api.db;
  * not indicate a database error.
  */
 public class NoSuchMessageException extends DbException {
-
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/NoSuchTransportException.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
 /**
  * Thrown when a database operation is attempted for a transport that is not in
@@ -6,5 +6,4 @@ package org.briarproject.api.db;
  * not indicate a database error.
  */
 public class NoSuchTransportException extends DbException {
-
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/Transaction.java

@@ -1,14 +1,17 @@
-package org.briarproject.api.db;
+package org.briarproject.bramble.api.db;
 
-import org.briarproject.api.event.Event;
+import org.briarproject.bramble.api.event.Event;
 
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+import javax.annotation.concurrent.NotThreadSafe;
+
 /**
  * A wrapper around a database transaction. Transactions are not thread-safe.
  */
+@NotThreadSafe
 public class Transaction {
 
 	private final Object txn;

bramble-api/src/main/java/org/briarproject/bramble/api/event/Event.java

@@ -0,0 +1,7 @@
+package org.briarproject.bramble.api.event;
+
+/**
+ * An abstract superclass for events.
+ */
+public abstract class Event {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/event/EventBus.java

@@ -0,0 +1,22 @@
+package org.briarproject.bramble.api.event;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface EventBus {
+
+	/**
+	 * Adds a listener to be notified when events occur.
+	 */
+	void addListener(EventListener l);
+
+	/**
+	 * Removes a listener.
+	 */
+	void removeListener(EventListener l);
+
+	/**
+	 * Notifies all listeners of an event.
+	 */
+	void broadcast(Event e);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/event/EventListener.java

@@ -0,0 +1,16 @@
+package org.briarproject.bramble.api.event;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+/**
+ * An interface for receiving notifications when events occur.
+ */
+@NotNullByDefault
+public interface EventListener {
+
+	/**
+	 * Called when an event is broadcast. Implementations of this method must
+	 * not block.
+	 */
+	void eventOccurred(Event e);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/identity/Author.java

@@ -1,11 +1,19 @@
-package org.briarproject.api.identity;
+package org.briarproject.bramble.api.identity;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.UnsupportedEncodingException;
 
-/** A pseudonym for a user. */
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A pseudonym for a user.
+ */
+@Immutable
+@NotNullByDefault
 public class Author {
 
-	public enum Status { ANONYMOUS, UNKNOWN, UNVERIFIED, VERIFIED, OURSELVES }
+	public enum Status {ANONYMOUS, UNKNOWN, UNVERIFIED, VERIFIED, OURSELVES}
 
 	private final AuthorId id;
 	private final String name;
@@ -25,17 +33,23 @@ public class Author {
 		this.publicKey = publicKey;
 	}
 
-	/** Returns the author's unique identifier. */
+	/**
+	 * Returns the author's unique identifier.
+	 */
 	public AuthorId getId() {
 		return id;
 	}
 
-	/** Returns the author's name. */
+	/**
+	 * Returns the author's name.
+	 */
 	public String getName() {
 		return name;
 	}
 
-	/** Returns the public key used to verify the pseudonym's signatures. */
+	/**
+	 * Returns the public key used to verify the pseudonym's signatures.
+	 */
 	public byte[] getPublicKey() {
 		return publicKey;
 	}

bramble-api/src/main/java/org/briarproject/bramble/api/identity/AuthorConstants.java

@@ -1,8 +1,10 @@
-package org.briarproject.api.identity;
+package org.briarproject.bramble.api.identity;
 
 public interface AuthorConstants {
 
-	/** The maximum length of an author's name in UTF-8 bytes. */
+	/**
+	 * The maximum length of an author's name in UTF-8 bytes.
+	 */
 	int MAX_AUTHOR_NAME_LENGTH = 50;
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/identity/AuthorFactory.java

@@ -1,5 +1,8 @@
-package org.briarproject.api.identity;
+package org.briarproject.bramble.api.identity;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
 public interface AuthorFactory {
 
 	Author createAuthor(String name, byte[] publicKey);

bramble-api/src/main/java/org/briarproject/bramble/api/identity/AuthorId.java

@@ -1,13 +1,18 @@
-package org.briarproject.api.identity;
+package org.briarproject.bramble.api.identity;
 
-import org.briarproject.api.UniqueId;
+import org.briarproject.bramble.api.UniqueId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.nio.charset.Charset;
 
+import javax.annotation.concurrent.ThreadSafe;
+
 /**
  * Type-safe wrapper for a byte array that uniquely identifies an
- * {@link org.briarproject.api.identity.Author Author}.
+ * {@link Author}.
  */
+@ThreadSafe
+@NotNullByDefault
 public class AuthorId extends UniqueId {
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/identity/IdentityManager.java

@@ -0,0 +1,38 @@
+package org.briarproject.bramble.api.identity;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.identity.Author.Status;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface IdentityManager {
+
+	/**
+	 * Stores the local pseudonym.
+	 */
+	void registerLocalAuthor(LocalAuthor a) throws DbException;
+
+	/**
+	 * Returns the cached main local identity, non-blocking, or loads it from
+	 * the db, blocking
+	 */
+	LocalAuthor getLocalAuthor() throws DbException;
+
+	/**
+	 * Returns the cached main local identity, non-blocking, or loads it from
+	 * the db, blocking, within the given Transaction.
+	 */
+	LocalAuthor getLocalAuthor(Transaction txn) throws DbException;
+
+	/**
+	 * Returns the trust-level status of the author
+	 */
+	Status getAuthorStatus(AuthorId a) throws DbException;
+
+	/**
+	 * Returns the trust-level status of the author
+	 */
+	Status getAuthorStatus(Transaction txn, AuthorId a) throws DbException;
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/identity/LocalAuthor.java

@@ -1,6 +1,14 @@
-package org.briarproject.api.identity;
+package org.briarproject.bramble.api.identity;
 
-/** A pseudonym for the local user. */
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A pseudonym for the local user.
+ */
+@Immutable
+@NotNullByDefault
 public class LocalAuthor extends Author {
 
 	private final byte[] privateKey;
@@ -13,7 +21,9 @@ public class LocalAuthor extends Author {
 		this.created = created;
 	}
 
-	/**  Returns the private key used to generate the pseudonym's signatures. */
+	/**
+	 * Returns the private key used to generate the pseudonym's signatures.
+	 */
 	public byte[] getPrivateKey() {
 		return privateKey;
 	}

bramble-api/src/main/java/org/briarproject/bramble/api/identity/event/LocalAuthorAddedEvent.java

@@ -0,0 +1,25 @@
+package org.briarproject.bramble.api.identity.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a local pseudonym is added.
+ */
+@Immutable
+@NotNullByDefault
+public class LocalAuthorAddedEvent extends Event {
+
+	private final AuthorId authorId;
+
+	public LocalAuthorAddedEvent(AuthorId authorId) {
+		this.authorId = authorId;
+	}
+
+	public AuthorId getAuthorId() {
+		return authorId;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/identity/event/LocalAuthorRemovedEvent.java

@@ -0,0 +1,25 @@
+package org.briarproject.bramble.api.identity.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a local pseudonym is removed.
+ */
+@Immutable
+@NotNullByDefault
+public class LocalAuthorRemovedEvent extends Event {
+
+	private final AuthorId authorId;
+
+	public LocalAuthorRemovedEvent(AuthorId authorId) {
+		this.authorId = authorId;
+	}
+
+	public AuthorId getAuthorId() {
+		return authorId;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/invitation/InvitationConstants.java

@@ -0,0 +1,20 @@
+package org.briarproject.bramble.api.invitation;
+
+public interface InvitationConstants {
+
+	/**
+	 * The connection timeout in milliseconds.
+	 */
+	long CONNECTION_TIMEOUT = 60 * 1000;
+
+	/**
+	 * The confirmation timeout in milliseconds.
+	 */
+	long CONFIRMATION_TIMEOUT = 60 * 1000;
+
+	/**
+	 * The number of bits in an invitation or confirmation code. Codes must fit
+	 * into six decimal digits.
+	 */
+	int CODE_BITS = 19;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/invitation/InvitationListener.java

@@ -1,4 +1,4 @@
-package org.briarproject.api.invitation;
+package org.briarproject.bramble.api.invitation;
 
 /**
  * An interface for receiving updates about the state of an

bramble-api/src/main/java/org/briarproject/bramble/api/invitation/InvitationState.java

@@ -1,5 +1,15 @@
-package org.briarproject.api.invitation;
+package org.briarproject.bramble.api.invitation;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A snapshot of the state of an {@link InvitationTask}.
+ */
+@Immutable
+@NotNullByDefault
 public class InvitationState {
 
 	private final int localInvitationCode, remoteInvitationCode;
@@ -7,13 +17,14 @@ public class InvitationState {
 	private final boolean connected, connectionFailed;
 	private final boolean localCompared, remoteCompared;
 	private final boolean localMatched, remoteMatched;
+	@Nullable
 	private final String contactName;
 
 	public InvitationState(int localInvitationCode, int remoteInvitationCode,
 			int localConfirmationCode, int remoteConfirmationCode,
 			boolean connected, boolean connectionFailed, boolean localCompared,
 			boolean remoteCompared, boolean localMatched,
-			boolean remoteMatched, String contactName) {
+			boolean remoteMatched, @Nullable String contactName) {
 		this.localInvitationCode = localInvitationCode;
 		this.remoteInvitationCode = remoteInvitationCode;
 		this.localConfirmationCode = localConfirmationCode;
@@ -67,6 +78,7 @@ public class InvitationState {
 		return remoteMatched;
 	}
 
+	@Nullable
 	public String getContactName() {
 		return contactName;
 	}

bramble-api/src/main/java/org/briarproject/bramble/api/invitation/InvitationTask.java

@@ -1,6 +1,11 @@
-package org.briarproject.api.invitation;
+package org.briarproject.bramble.api.invitation;
 
-/** A task for exchanging invitations with a remote peer. */
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+/**
+ * A task for exchanging invitations with a remote peer.
+ */
+@NotNullByDefault
 public interface InvitationTask {
 
 	/**
@@ -9,10 +14,14 @@ public interface InvitationTask {
 	 */
 	InvitationState addListener(InvitationListener l);
 
-	/** Removes the given listener. */
+	/**
+	 * Removes the given listener.
+	 */
 	void removeListener(InvitationListener l);
 
-	/** Asynchronously starts the connection process. */
+	/**
+	 * Asynchronously starts the connection process.
+	 */
 	void connect();
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/invitation/InvitationTaskFactory.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.invitation;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+/**
+ * Creates tasks for exchanging invitations with remote peers.
+ */
+@NotNullByDefault
+public interface InvitationTaskFactory {
+
+	/**
+	 * Creates a task using the given local and remote invitation codes.
+	 */
+	InvitationTask createTask(int localCode, int remoteCode);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/KeyAgreementConnection.java

@@ -1,9 +1,15 @@
-package org.briarproject.api.keyagreement;
+package org.briarproject.bramble.api.keyagreement;
 
-import org.briarproject.api.TransportId;
-import org.briarproject.api.plugins.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
 public class KeyAgreementConnection {
+
 	private final DuplexTransportConnection conn;
 	private final TransportId id;
 

bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/KeyAgreementConstants.java

@@ -0,0 +1,36 @@
+package org.briarproject.bramble.api.keyagreement;
+
+public interface KeyAgreementConstants {
+
+	/**
+	 * The current version of the BQP protocol.
+	 */
+	byte PROTOCOL_VERSION = 2;
+
+	/**
+	 * The length of the record header in bytes.
+	 */
+	int RECORD_HEADER_LENGTH = 4;
+
+	/**
+	 * The offset of the payload length in the record header, in bytes.
+	 */
+	int RECORD_HEADER_PAYLOAD_LENGTH_OFFSET = 2;
+
+	/**
+	 * The length of the BQP key commitment in bytes.
+	 */
+	int COMMIT_LENGTH = 16;
+
+	long CONNECTION_TIMEOUT = 20 * 1000; // Milliseconds
+
+	/**
+	 * The transport identifier for Bluetooth.
+	 */
+	int TRANSPORT_ID_BLUETOOTH = 0;
+
+	/**
+	 * The transport identifier for LAN.
+	 */
+	int TRANSPORT_ID_LAN = 1;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/KeyAgreementListener.java

@@ -1,6 +1,6 @@
-package org.briarproject.api.keyagreement;
+package org.briarproject.bramble.api.keyagreement;
 
-import org.briarproject.api.data.BdfList;
+import org.briarproject.bramble.api.data.BdfList;
 
 import java.util.concurrent.Callable;